... attached. Fir.1 Three-dimensional Magnetic Induction Line Demonstrator 1, Bar Magnet, 2, Bracket Plate, 3,Riser, 4, Horseshoe MagnetTheoryWhen ... Put the horseshoe magnet into the groove of raised riser, install the five pieces of small risers and buckle tightlyExperiment Method2 ... fingers to be in a state of irregular arrangement2.2 Install the bar or horseshoe magnet, the small fingers on each riser ...